const PI = 3.14159265358979324;

function transformLat(x: number, y: number) {
  let ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
  ret += ((20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0) / 3.0;
  ret += ((20.0 * Math.sin(y * PI) + 40.0 * Math.sin((y / 3.0) * PI)) * 2.0) / 3.0;
  ret += ((160.0 * Math.sin((y / 12.0) * PI) + 320 * Math.sin((y * PI) / 30.0)) * 2.0) / 3.0;
  return ret;
}

function transformLon(x: number, y: number) {
  let ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
  ret += ((20.0 * Math.sin(6.0 * x * PI) + 20.0 * Math.sin(2.0 * x * PI)) * 2.0) / 3.0;
  ret += ((20.0 * Math.sin(x * PI) + 40.0 * Math.sin((x / 3.0) * PI)) * 2.0) / 3.0;
  ret += ((150.0 * Math.sin((x / 12.0) * PI) + 300.0 * Math.sin((x / 30.0) * PI)) * 2.0) / 3.0;
  return ret;
}

// 坐标转换
function delta(lat: number, lon: number) {
  const a = 6378245.0; //  a: 卫星椭球坐标投影到平面地图坐标系的投影因子。
  const ee = 0.00669342162296594323; //  ee: 椭球的偏心率。
  let dLat = transformLat(lon - 105.0, lat - 35.0);
  let dLon = transformLon(lon - 105.0, lat - 35.0);
  const radLat = (lat / 180.0) * PI;
  let magic = Math.sin(radLat);
  magic = 1 - ee * magic * magic;
  const sqrtMagic = Math.sqrt(magic);
  dLat = (dLat * 180.0) / (((a * (1 - ee)) / (magic * sqrtMagic)) * PI);
  dLon = (dLon * 180.0) / ((a / sqrtMagic) * Math.cos(radLat) * PI);
  return { lat: dLat, lon: dLon };
}

// 判断是否为国外坐标
function outOfChina(lat: number, lon: number) {
  if (lon < 72.004 || lon > 137.8347) {
    return true;
  }
  if (lat < 0.8293 || lat > 55.8271) {
    return true;
  }
  return false;
}

// GPS---高德 / WGS-84 to GCJ-02
export default function gcjEncrypt(wgsLat: number, wgsLon: number) {
  if (outOfChina(wgsLat, wgsLon)) {
    return { lat: wgsLat, lon: wgsLon };
  }

  const d = delta(wgsLat, wgsLon);
  return { lat: wgsLat + d.lat, lon: wgsLon + d.lon };
}

// GCJ-02 - WGS-84
export function gcjDecrypt(gcjLat: number, gcjLon: number) {
  if (outOfChina(gcjLat, gcjLon)) {
    return { lat: gcjLat, lon: gcjLon };
  }

  const d = delta(gcjLat, gcjLon);
  return { lat: gcjLat - d.lat, lon: gcjLon - d.lon };
}

/**
 * 根据坐标计算长度
 */
export function calcDistance(lng1: number, lat1: number, lng2: number, lat2: number) {
  const radLat1 = (lat1 * Math.PI) / 180.0;
  const radLat2 = (lat2 * Math.PI) / 180.0;
  const a = radLat1 - radLat2;
  const b = (lng1 * Math.PI) / 180.0 - (lng2 * Math.PI) / 180.0;
  let s =
    2 *
    Math.asin(
      Math.sqrt(
        Math.sin(a / 2) ** 2 + Math.cos(radLat1) * Math.cos(radLat2) * Math.sin(b / 2) ** 2,
      ),
    );
  s *= 6378.137; // EARTH_RADIUS;
  s = Math.round(s * 10000) / 10000; // 输出为公里
  return s * 1000; // 输出为米
}
